Multiple Quality Control Pathways Limit Non-protein Amino Acid Use by Yeast Cytoplasmic Phenylalanyl-tRNA Synthetase.
J Biol Chem
; 291(30): 15796-805, 2016 07 22.
Article
em En
| MEDLINE
| ID: mdl-27226603
ABSTRACT
Non-protein amino acids, particularly isomers of the proteinogenic amino acids, present a threat to proteome integrity if they are mistakenly inserted into proteins. Quality control during aminoacyl-tRNA synthesis reduces non-protein amino acid incorporation by both substrate discrimination and proofreading. For example phenylalanyl-tRNA synthetase (PheRS) proofreads the non-protein hydroxylated phenylalanine derivative m-Tyr after its attachment to tRNA(Phe) We now show in Saccharomyces cerevisiae that PheRS misacylation of tRNA(Phe) with the more abundant Phe oxidation product o-Tyr is limited by kinetic discrimination against o-Tyr-AMP in the transfer step followed by o-Tyr-AMP release from the synthetic active site. This selective rejection of a non-protein aminoacyl-adenylate is in addition to known kinetic discrimination against certain non-cognates in the activation step as well as catalytic hydrolysis of mispaired aminoacyl-tRNA(Phe) species. We also report an unexpected resistance to cytotoxicity by a S. cerevisiae mutant with ablated post-transfer editing activity when supplemented with o-Tyr, cognate Phe, or Ala, the latter of which is not a substrate for activation by this enzyme. Our phenotypic, metabolomic, and kinetic analyses indicate at least three modes of discrimination against non-protein amino acids by S. cerevisiae PheRS and support a non-canonical role for SccytoPheRS post-transfer editing in response to amino acid stress.
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01-internacional
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Base de dados:
MEDLINE
Assunto principal:
Fenilalanina-tRNA Ligase
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Saccharomyces cerevisiae
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Proteínas de Saccharomyces cerevisiae
Idioma:
En
Revista:
J Biol Chem
Ano de publicação:
2016
Tipo de documento:
Article